Window glass of an automobile vehicle is generally closed or opened by vertical movement for ventilation or to talk with a vehicle outsider. A guide member known as a glass run channel is provided between a window glass and a window frame in order to enable closing or opening of the window glass in tight (liquid-tight) relationship with the window frame while facilitating the closing or opening by vertical movement of the window glass.
The conventional glass run channel is composed of a soft synthetic resin such as a soft vinyl chloride resin or a vulcanized rubber such as an ethylene/propylene/diene copolymer rubber. The glass run channel comprises a glass run channel body, this glass run channel body comprising a bottom wall and side walls extending from two opposite edges of the bottom wall, the glass run channel body having a substantially U-shaped section and provided with a groove, and tonguelike draining parts protruding from vicinities of distal edges of the side walls toward the bottom wall of the glass run channel body so as to become proximate to each other.
The conventional glass run channel has a window glass sliding part whose surface is laminated with, for example, a nylon film by bonding in order to improve the parting of the window glass from the draining part and in order to prevent fouling of the window glass. The window glass sliding part is also embossed prior to or subsequent to the lamination of the nylon film, etc. in order to reduce the area of contact with the window glass.
In the above glass run channel, a surface material such as the nylon is not adherent to the above soft synthetic resin or vulcanized rubber. Therefore, the steps are required such that the glass run channel body is formed using the soft synthetic resin or vulcanized rubber, an adhesive is applied to the formed glass run channel body and the glass run channel body is laminated with the film of, for example, nylon. Further, embossing must be carried out prior to or subsequent to the lamination. Thus, disadvantageously, the number of required steps is large and the workload is intense.
Moreover, the above glass run channel is to be produced by a process including the lamination with the use of an adhesive, so that, disadvantageously, not only is the durability thereof poor but also a peeling is likely to occur between the surface film layer and the substrate as a result of aging, outdoor exposure, etc. Further, the uneven surface pattern which can be formed by embossing is not fully satisfactory in a combination of fineness and uniformity, so that there remain points to be improved in the tight contactability of the window glass sliding part with a window glass as exhibited when the window glass is held closed and in the supple slide between the window glass sliding part and window glass as exhibited when the window glass is opened.
The inventors made extensive and intensive studies with a view toward resolving the above problems of the glass run channel; found that a glass run channel which was excellent in the durability, tight contactability with a window glass exhibited when the window glass was held closed and supple window glass slide exhibited when the window glass was opened could be fabricated with simple productive operations by selecting a thermoplastic elastomer composed of a crystalline polyolefin and a rubber as an elastomer forming at least a window glass sliding part of the glass run channel and laminating a specified ultrahigh molecular weight polyolefin composition layer onto a layer of the thermoplastic elastomer by thermal fusion bonding; and proposed a novel glass run channel (see Japanese Patent Laid-open Publication Nos. 5(1993)-4522 and 5(1993)-4308).
However, this glass run channel has encountered a problem such that the use of an ultrahigh molecular weight polyolefin such as an ultrahigh molecular weight polyethylene alone in the ultrahigh molecular weight polyolefin composition layer causes the ultrahigh molecular weight polyolefin composition layer to crease because of a high rigidity to thereby deteriorate the product appearance when the glass run channel is twisted or bent at the time of, for example, assembling the product, glass run channel, into an automobile body.
The inventors have conducted investigations with a view toward overcoming this problem. As a result, it has been found that a glass run channel capable of exhibiting the performance of ultrahigh molecular weight polyolefin, in which the ultrahigh molecular weight polyolefin composition layer is not creased when the glass run channel is twisted or bent can be obtained by employing an ultrahigh molecular weight polyolefin composition comprising an ultrahigh molecular weight polyolefin and an olefinic thermoplastic elastomer. The present invention has been completed on the basis of this finding.